1. Field of Invention
The invention relates to a gamma correction method for correcting digital images and, in particular, to a gamma correction method that employs the locality statistics characteristic.
2. Related Art
Gamma corrections pertain to the control and adjustment of colors in an image input/output (IO) system. It often relates to the control of the brightness in an image. If the output display of an image is not corrected in this way, the presented image often looks dim or the colors do not saturate because of the distortion occurring during signal transmissions. The procedure mainly adjusts the color output of the image by tuning the gamma values. A common method is to insert a step of checking a gamma table during the image IO process. Normally, a pixel is comprised of three subpixels representing the three primitive colors: red, green and blue. Therefore, the correction requires a red gamma table, a green gamma table, and a blue gamma table.
Taking a conventional gamma correction procedure as an example, at the same moment of inputting a digital image, the system separates the pixel into three subpixels of the three primitive colors and corrects them separately. After extracting the pixels in a digital image, the gamma tables of the respective colors are used to correct the colors. Each gamma table contains many sets of digital image subpixel values and the corresponding gamma correction values. When a digital image subpixel value is entered, the corresponding gamma correction value is obtained through a binary search. The gamma correction value is then stored in memory. This completes a table search correction procedure. However, it takes about 8 times of binary search clocks on the average to look for the corresponding gamma correction value for each subpixel. Therefore, each digital image pixel needs about 24 search clocks. This is very inefficient in practice.